Each year, hand injuries and disorders occur at an alarming rate, estimated at 16 million upper extremity hand-wrist injuries with two-thirds in individuals still in their productive years. Arthritic involvement, both degenerate and rheumatoid, in the fingers and thumb primarily involve women less than 65 years of age. The purpose of this study is to increase the basic understanding and clinical applications associated with one of the most important areas of hand surgery- joint replacement as part of a continued plan to understand functional forces in normal and abnormal fingers and thumb. Two groups of studies will be performed and the following hypotheses will be tested. The first study is an in vitro evaluation of finger joint replacement. The hypotheses to be tested are that 1. all resurfacing-type finger and thumb joint implants provide intrinsic stability equivalent to normal anatomic joints; 2. Resurfacing-type finger and thumb implants associated with ligament repair/construction restore normal stability in the finger and thumb joints; 3. All joint arthroplasties restore near normal tendon movement arms across the joint and are equivalent. The second study is an in vivo functional evaluation of patients with joint replacement. The first hypothesis is that proper joint replacement will improve and restore functional strength in the fingers and thumb. The second hypothesis is that proper joint replacement will improve and restore functional range of motion in the fingers and thumb. The third hypothesis is that proper joint replacement will improve and restore dexterity in the fingers and thumb while performing a specific functional test.